This invention relates to the partial oxidation of a liquid hydrocarbon fuel to produce synthesis gas. More specifically, it relates to a process for simultaneously producing two clean product streams of synthesis gas, one gas stream with a high and the other gas stream with a low, H.sub.2 O/dry gas mole ratio by the partial oxidation of heavy hydrocarbon feedstocks containing high metal concentrations.
When a heavy liquid hydrocarbon fuel containing high metal concentrations such as vacuum resid is reacted by partial oxidation, entrained in the hot, raw gas stream is particulate carbon and ash, i.e., nickel, vanadium, and iron compounds. After the raw gas stream is cleaned free from particulate matter, it is economically desirable to dispose of the particulate carbon in the gas generator. However, recent commercial experience in gasifying heavy feed stocks containing high metal concentrations with 100% soot recycle has shown that the convection type gas coolers in the system may be then subject to shutdown because of fouling. Deposits may plug the gas cooler tube inlets or may collect downstream in the low-temperature sections of the gas cooler tubes. These problems and others are now avoided by the subject invention.
The hot raw effluent gas stream from the reaction zone of a partial oxidation gas generator may comprise principally H.sub.2, CO, CO.sub.2, and H.sub.2 O together with other gaseous constituents, and minor amounts of entrained particulate matter, i.e., particulate carbon and ash. The hot, raw effluent gas must be cooled and cleaned to produce synthesis gas or fuel gas. Synthesis gas is important commercially as a source of feed gas for the synthesis of hydrocarbons or oxygen containing organic compounds, or for producing hydrogen or ammonia.
Entrained particulate carbon and ash may be removed from the raw effluent gas by quenching and scrubbing with water such as described in coassigned U.S. Pat. No. 3,232,728. Cleaning the effluent gas by scrubbing with an oil-carbon slurry is described in coassigned U.S. Pat. No. 3,639,261. Recovery of the soot, from carbon-water dispersions in a carbon-recovery facility is described in coassigned U.S. Pat. Nos. 2,999,741; 2,992,906; 3,044,179; and 4,134,740. Typical decanting procedures are described in coassigned U.S. Pat. Nos. 3,980,592 and 4,014,786. These coassigned U.S. Patents are incorporated herein by reference.